The present invention relates generally to methods and apparatus for electrical microcurrent stimulation therapy, and more particularly to methods and apparatus for providing electrical microcurrent stimulation around an eye to combat visual system diseases, such as macular degeneration.
Chronic pain is a problem for millions of individuals throughout the world. One method of treating such pain is to provide microcurrent stimulation around or near the areas where the pain is occurring. Microcurrent, which typically is defined as current below 1 milliamp, can provide rapid and long-lasting pain relief for a wide variety of pain syndromes. Generally, microcurrent stimulation therapy typically comprises applying a current in the range of about 20 to about 300 microamps to the affected area. The current or microcurrent blocks neuronal transmission of pain signals and stimulates the release of endorphins to help relieve the pain in chronic and acute pain patients.
While the current level can be an important factor in microcurrent stimulation therapy, frequency modulation and the waveform of the electrical signal are also important. Some electrical stimulation therapy devices currently known in the art typically allow the user to manually adjust the frequency ranges and types of waveform signals applied to the patient. For example, the MicroStim 400 device, manufactured by MicroStim, Inc., located in Tamarac, Fla., features a combination of a carrier waveform having a modulated frequency thereon. The MicroStim device is covered by U.S. Pat. No. 4,989,605, issued on Feb. 5, 1991 to Joel Rossen and entitled "Transcutaueous Electrical Nerve Stimulation (TENS) Device", the contents of which is incorporated herein by reference. The theory behind the MicroStim 400 device is that the carrier wave is designed to take the modulated frequency deep into the body for consistent and rapid pain relief. However, a disadvantage of the MicroStim 400 device is that the signal that it generates produces most of its power at individual frequencies 105. That is, when viewing the signal produced by the MicroStim 400 in the frequency domain, the majority of the power output from the signal resides at discrete frequencies. Accordingly, the therapeutic effect of the signal may not be maximized.
Another device which can be used for microcurrent stimulation therapy is the Amrex Z-Stim device manufactured by Amrex, Corp. of Carson, Calif. The Z-Stim device is a multi-signal interferential stimulator that provides multiple swept frequency sinusoidal signals. The applications for sinusoidal signals are more appropriate for muscle stimulation and addressing problems associated with pain, edema and rehabilitation for certain neuromuscular and orthopedic problems.
In addition to chronic pain relief, microcurrent therapy is being used to treat a number of visual system diseases, including macular degeneration and retinitis pigmentosa.
Age-related macular degeneration (AMD) is the leading cause of legal blindness in the United States in persons over 65 years old. According to a March 1997 Review of Optometry Journal, 10% of our population over age 52 has AMD and 33% of individuals over age 75 have AMD. It is estimated that more than 13 million Americans now have AMD and that, by the time the Baby Boomers reach age 65, there will be over 30 million cases of AMD, almost 25% of our population over 65.
Normal retinal cell function is a photochemical reaction converting light energy to an electrical impulse which travels to the brain and vision occurs. With AMD and other visual system diseases, diseased, inflamed retinal cells eventually lose cell function. Adenosine triphosphate (ATP) levels drop, protein synthesis drops, the electrical resistance goes up, and cell membrane electrical potential goes down. Basically, the cells seem to go dormant for a time before they die. It is believed that, if electrical stimulation is provided to the cells before they die, blood vessel permeability is increased, a more normal cellular electrical potential will be achieved, the ATP levels will increase, protein synthesis will occur again, and normal cell metabolism will be restored. In addition, electrical stimulation appears to have a healing effect on the small blood vessels in the retina, promoting a more efficient delivery of nutrients to the retinal cells and a more efficient uptake of proteins that can accumulate on the retina. Thus, it is believed that microcurrent stimulation will help rejuvenate the cells in the retina to slow or stop degeneration of the eye due to AMD. With the proper microcurrent stimulation waveform and therapy procedures, AMD may be slowed or stopped in a large number of people suffering from the disease.
While microcurrent stimulation therapy has been used to treat AMD and other visual system diseases, the methods and apparatus used in the prior art do not appear to maximize the therapeutic effect. For example, as mentioned briefly above, the devices for providing microcurrent stimulation therapy are limited in the types of waveforms and frequency ranges which they may provide for therapy.